Wolf's Motorhome Modifications
... and Other Stuff
Saturn Flash Relay Mods for Use With LED Bulbs
When hooked up to my motorhome, my Saturn's lights are not as bright as I would like them to be. I decided to try LEDs. Using LEDs would drop the current in the long run of wire between the motorhome and the car. As that wire has resistance, voltage ends up being lower at the Saturn bulb sockets. This results in dimmer lights. By using LEDs, the current is significantly lower, the voltage drop is less and the lights are brighter.
And that is what happened. My lights
while towing are significantly brighter.
One
problem occurs when the loss of current confuses the flash relay. The IC
that controls the flasher checks to see if any bulbs are burned out. If
any bulb is burned out, it flashes the relay at double speed to alert the driver to the
problem.
The LED bulbs take less current and the flasher thinks a bulb is burned out. The schematic and the data sheet, available here, for the IC shows that pin 7 is sampled to check for bulb outages. If a bulb is out, it flashes quickly. By cutting pin seven from the board the flash relay is fooled into thinking all is well. A few sites say to jumper it to pin 6. That advice is incorrect. Just cut it free.
Don't put resistors across the LEDs
to simulate bulbs. It is counterproductive. Why heat up the
resistors, drawing current, lowering voltage and create all kinds of problems
the LEDs are supposed to fix?
I cut pin 7 from the board using a small knife.
Be sure to get an aftermarket flasher. I bought mine at NAPA for $15.00. Saturn wanted $31 and the OEM unit is potted. Potted means the electronics have been sealed in a waterproofing glue.
I put a label on the modified flasher so that
a future need for replacement won't generate confusion.
